A.L.
My mom uses a pressure cooker for two things
-to cook a roast quickly. She can pull it out of the deep freeze after breakfast, and it's done in time for lunch.
-for canning - because it's big, and she can fit all of her jars in it at once for boiling.
I don't know what other use it has. If this is appealing to you, then go for it. Personally, I'd just stick with crockpot and have the roast for Sunday dinner instead of Sunday lunch. Even if they weren't cost-prohibitive, I can't justify rearranging my pantry and cabinets to store something that big, that I'm only MAYBE going to use occasionally.